Aim: How do we apply double-angle formulas to solve trigonometric equations?
At the end of this lesson, you will be able to...
state the trigonometric formulas involving double angles
describe which double angle formula is needed to solve a trigonometric equation
solve trigonometric equations using double angle formulas
express solutions to the required degree of accuracy in the specified interval
OK, this lesson does not involve any videos. (I'm sure you're happy about that :) ). All you need to do is to substitute the double-angle function for it's equivalent and then solve like you did in previous lessons.
Classwork:
Find to the nearest degree the roots of cos2x - 2 cosx = 0 from 0<x<360. (Ans: 111 degrees or 249 degrees)
Find the values for x if sin2x - sinx = 0 on the interval 0<x<2 pi (Ans: 0, pi, pi/3, 5pi/3)
Journal entry: Since there are three expansion formulas for y = 2cosa, how do you decide which formula substitution is best to use when using a trig equation containing cos 2a?
At the end of this lesson, you will be able to...
OK, this lesson does not involve any videos. (I'm sure you're happy about that :) ). All you need to do is to substitute the double-angle function for it's equivalent and then solve like you did in previous lessons.
Classwork:
Homework: Complete 3-19 odd
Double_angle_app.JPG
Answers:
A-Double_Angle_App.JPG
Journal entry: Since there are three expansion formulas for y = 2cosa, how do you decide which formula substitution is best to use when using a trig equation containing cos 2a?